Flasher



FLASHER Filed Nov.' 15, 1952 March 16,1937.

5 Sheets-Sheet 1 AAA] jMMv gfwgsggH v/vvvv/v 703 gg 50 62 77 l 72 103 @Q AMA 1 AA/A MmhA 16, 1937. c. H. LARsoN FLASHER Filed Nv. l5, 1932 3 Sheets-Sheet 2 March 16, 1937. H- LARSON 2,073,969

FLASHER Filed Nov. 15, 1932 3 Sheets-Sheet 3 Patented Mar. 16, 1937 UNITED STATESg PATENT GFFICE FLASHER Application Novemberis, 1932, sei-iai No. 642,746

. 10 Claims.

There are two types of highway crossing signalsin general use which conform to the recommended practice. The first of these is the iiashing light type inv which two lamps, spaced approximately two and one-half feet apart, `are mounted on a' horizontal support and alternately flashed; and the other,` known as the wig-Wag type in which a pendulum disk is oscillated and carries on its end a red light. It is the first of these`two types of crossing signals to which this invention is directed.

Electrical apparatus commonly used for producing the intermittent flashes of the lamps is illustrated and described in American Railway l5 Signaling Principles and Practices, Chapter 6, Direct current relays, published by the Signal Section, A. R. A., 30 Vesey St., New York, N. Y. It will be observed that these relays are all of the mechanical type and 'are consequently open to the usual objections, the principal one of which is that the contacts become pitted or worn and require frequent attention.

In the asher relay of this invention, all rne-4 chanical contacts have been eliminated and mercury switches are used in their place. The

fact that all electrical contacts of the mercury o switch relay are hermetically sealed within a glass envelope and in consequence are not subject to the deteriorating @effects .of Vthe atmosphere, is but one of the advantages of this type of relay.

Other advantages which may be briefly mentioned reside in the elimination of bearings and movable parts, the constant and extremelylow contact resistance yunaffected by temperature changes of below zero to 300 above zero, the lack of wear on the contact material, the noiseless operation on both alternating current and direct current, economy of space due to 40 compact mounting, and the complete elimination of the necessity for inspection and maintenance.

As the disclosure proceeds, it will also beA seen vthat the flasher relay of this invention is much (Cl. 20o- 97) self-acting intermittent circuit breaker in a control circuit;

Figs. 5A and 6 illustrate other positions of the electro-magnetic switch in the main circuit;

Fig. 7 shows a modication in which front' and back contact mercury switches are-substituted for the three electrode switch shown in the preferred form of the invention; X Fig. 8 is a. view similar to Fig. 'l showing the switch parts in the position they assume when. the associated coil is energized; Eig. 9 is a rear view of 'the relay mounting; and

Fig. 10 is a diagrammatic perspective view of the relay, its housing, and a crossing signal connected to the relay.

. The specific disclosure of preferred and modied forms of the invention is not to be nterpreted as imposing limitations upon the appended claims except as may be4 required by the prior art.

Referring first to Fig. 1, a preferred form of the invention is illustrated as applied to a dou- `ble track road with traflic in the direction of the arrows. The electrical apparatus consists of a track circuit, a control circuit anda main circuit, the latter two ofwhich are held open by the track circuit until a train comeswithin a certain distance `of the crossing which is to be protected. The control circuit includes a selfacting intermittent circuit breaker generally designated I0 which opens and closes vthe control circuit at regular intervals. The main circuit includes the-lamps II and I2 which are alternately ashed by an electromagnetic switch I3 which is governed by the control circuit. It will be understood that the lamps Il and I2 are'mounted on a horizontal support I4 (Fig. 10) adjacent to the crossing which is being protected. Theilasher relay generally desi which combines the control land main circuits constitutes a unit that may be mounted in a suitable box alongside the track.

Track circuit In Fig. 1, there is illustrated a suitable track circuit for a double track road with traflic on each track in one direction only. 'I'he track I6, with traic to the left (Figyl) is provided with insulated rail joints Il and lswhich enable a atea I5, `40

potential to be applied between the opposed rails ,of the track to normally maintain the coil I 9 of the track relay, generally designated 20, in energized condition. The potentialis applied through a transformer 2I` which reduces the 110 volt source of alternating current to 10 volts. At a point adjacent the insulated rail joint I1, a transformer 22 is connected across the opposed rails to complete the circuit, the secondary coil 23 of the transformer being connected to a rectif-ler 24 which in turn is connected to the coil I9. When the train enters the section of track between the insulated joints I8 and I1, the circuit between the transformers 2l and 22`wil1 be short circuited, and in consequencethe relay coll I9 becomes de-energized, allowing the armatures 25 and 26,to fall on their respective contacts 21 and 2 8.

In alike manner, the track 29 whose traflic is to the right, Fig. 1, is provided with insulated rail joints 30 and 3|. A potential is applied across the opposed rails of the track as before, the electrical energy being derived from a 110 volt line connected to a transformer 32 which reduces the voltage to 10 volts. A transformer 33 connected across the opposed rails adjacent the insulated rail joint 3l completes the circuit and through its secondary coil 34 supplies energy to the rectifier 35, which in turn energizes the relay coil 36. When the train enters the sec'- tion of track between the insulated rail joints 30 and 3|, the circuit between the transformers 32 and 33 is shorted and in consequence, the armatures 31 and 38 are permitted to fall upon their respective contacts" 39 and 4D.

The armatures 25 and 31 are electrically connected to each other and to the conductor 4I which is in the control circuit. The contacts 21 and 39 are also connected to each other and to the conductor 42 in the control circuit. The control circuit is, therefore, held open by the relay coils I9 and 36 whenever the tracks I6 and 29 are clear between the insulated rail joints I8 and I1, and 30 and 3|, respectively, but as soon as a train enters either of these sections, one

of the coils of the track relays 20 completes the control circuit.

In a like manner, the main circuit is held open until a train short circuits the track circuit atwhich time either .the armature 26 falls upon the contact 28, or the armature 33 falls upon the contact 40. Since the armatures 26 and 38 are electrically connected to each other arid to a conductor 43 in the main circuit, and since the contacts 28 and 40` are also connectedto each other and to a conductor 44 i'n the main circuity the falling of either armature upon its associated contact will close the main circuit.

It is,l of course, understood that .when a train on track I6 passes the insulated rail joint I1, or'a train on track 29 passes the insulated rail joint 3I,'the track circuit is again established and the control and main circuits are broken.

Control circuit The purpose of the control circuit is to in- -termittently energize the electromagnetic switch I3. This is accomplished by providing a selfacting *intermittent circuit breaker I in the control circuit. The control circuit is energized by a battery` 45 although any other suitable'.

source of current may be employed, if desired. Two solenoids 46 and 41 connected in series Aare associated with the circuit breaker I-IJ, and

twodother solenoids 48 and 49 also connected in series are associated with the `electro-magnetic switch I3. The two groups of ,solenoids however, are connectedi'n parallel as will later be seen. v

The circuit breaker I6 comprises e -glass envelope 50 vertically mounted between pole pieces I and 52, the former being associated with the solenoid 41 and the latter with the solenoid 46. As the two solenoids are connected by a bar of magnetic material 53, a magnetic circuit is formed which is closed except for the air gap between the pole piecesy 5I and 52.

A quantityv of mercury 54 is placed in th envelope to bridge the electrodes 55 and 56 when the displacer 51, which is made vof magnetic material, is in the position shown in Fig. 1. The electrode 56 is connected by a conductor 58 to the conductor 59 which joins solenoid 46 with solenoid 48, and the electrode 55 connects with the conductor 4I so that when the electrodes are bridged by the mercury, the closing of the control circuit by the track relay 20 will immediately energize the solenoids 46 and 41. The circuit is then traceablefrom the battery through the conductor 60, solenoids 41 and 46, conductor 59, conductor 58, electrode 56, mercury 54, electrode 55, conductor 4I, armature 31 or 25, contact 39 or 21, conductor 42, and back to the battery.

However, as soon as the solenoids 46 and 41 are energized, the plunger 51 is lifted in its effort to close the air gap in the magnetic circuit. When this occurs, the mercury displaced by the lower portion 6I of the plunger recedes in the envelope and uncovers the electrode 55 (see Fig. 3) causing the control circuit to be broken. Thereupon the plunger 51 by its own weight falls once more to the position shown in Fig. l and reestablishes this circuit,` the intermittent making and breaking of thev circuit taking place -as long as the control circuit is closed by the de-energization of relay coil .I9-

Since the recommended practice of the American Railway Association requires that there be a certain time interval between the'light flashes, it is necessary to provide some means for controlling the intervals at which the control circuit is broken and reestablished. This is accomplished in the present invention by closing the top of the plunger' 51 and providing an aperture 62 into which a plug 63 is adapted to be adjustably seated.l A gas trap 64 is, therefore, formed with the only means of escape for the gas being past the plug 6,3 in the aperture 62. The plug may be tapered on one side so that as the plug is forced deeper into the plunger, the

aperture is proportionately reduced in size.

By this arrangement, when the solenoids 46 and 41 are energized, the plunger 51 is raised and picks up a quantity of mercury asv shown in curyfoccupies a positionsuch as shown in Fig.

3 vand the control circuit is broken. Thereupon, the plunger falls, as shown in Fig. 4, but once again the gas trap functions to delay the mercury in adjusting its level and in consequence, the mercury within the plunger is held away from the central electrode 55 until suilicient gas has escaped from the trap 64 to equalize the pressures on the inside and outside of the plunger. The switch then assumes the position shown in Fig. 1 and the operation is repeated.

The plunger 51 is preferably formed as a sleeve i' whichV the upper portion 85 is substantially thicker than the lower portion 8l. The purpose of this is to make the potential energy of the plunger when in its raised position substantially equal to the magnetic energy necessary to raise the plunger from its depressed position, for in this way the time interval for closing the circuit is substantially equal to the time interval for opening the circuit. Obviously, the plunger may assume a different form in accomplishing the same purpose, but preferably is in theform shown in Fig. 1 because in this form, the mass of the upper portion 65 of the plunger is close to the glass envelope where the magnetic eillciency of the solenoids 48 and 41 is maintained at a maximum.

By way of example, the plunger may have an overall length oiv three inches, an outside diameter of five-sixteenths of an inch at the upper portion 85. an inside diameter of %2 of an inch for the same portion. The outside diameter of the lower portion may be ,1/4 of an `inch and the inside diameter f/lg of an inch. With these dimensions, the lower portion 8| should consti tutef approximately one-half of the total length of the plunger.

Also, by way .of example, the solenoids 48 and 41 may be wound with 28 gauge, enameled copper wire having approximately 9000 turns per coil, ohmic resistance of 188 ohms per coil, with an actual current consumption of 26% milliiamperes, and a steady current consumption of 53 milliamperes.

The glass envelope is preferably filled with an inert gas such as helium, hydrogen, or the like, and springs 68 are provided `at the top and bottom of the plunger to prevent possible breakage of the envelope Lwhile the relay is being shipped.

In operation, the plunger drops to its lowermost position '(with. the bottom spring resting on the floor of the switch envelope) as soon as the coil is de-energized, without coming toa position of ildating equilibrium during the downward travel. This is effected by the distribu-4 tion of mass in the plunger and its .relation to the amount of mercury .in the envelope. Thus the action of the plunger is characterized by relactively quick, positive action in both directions. in response to the coil, `and the time delay in making or breaking the circuit through the electrodes is consequently directly dependent upon vthe operation of the gas trap in the plunger without' being functionally related to the speed of plunger travel.

The switch envelope is held within the poles 5I and 52 in any suitable manner. A convenient way for holding the 'switches in place is by slipping them through a bakelite sleeve 61 which has internal and outside diameters corresponding to the switch envelope and which is split longitudinally as shown at 88 to permit 'the sleeve to accommodate Vthe envelope. l Main circuit From. what 'has been said about the control circuit, itis obvious that the solenoids 48 and 49 is intended to mean,at similar time intervals" and is not necessarily to be construed as meaning simultaneous action.

The main circuit is energized by the secondary lamps II and I2.

coil 89 of atransformer 10, the primary coil 1I of which is connected to the usual 110 volt source of alternating current.

The electromagnetic switch I3 comprises a switch envelope 12 through the bottom of which electrodes 13, 14 and 15 are sealed. A quantity of mercury 16 is placed in the envelope and is adapted to bridge electrodes 13 and 15,- or elec-` trodes 14 and 15, according to the position of the .displacer 18 within' the envelope. Springs 11 are placed above and below the displacer to protect the envelope from possible injury.

In accordance withrailroad parlance, the electrode 13 will be termed a back contact because it establishes a connection when the associated solenoids are deenergized, and the electrode 14 will be termed a front contact because it establishes an electrical connection when the associated solenoids are energized.

'Ihe electrode 15 is connected by a conductor 19 with one side of .thesecondary coil4 89, the other side of the coil being connected by conductors 44 and 43 through the rtrack relay 20 and thence to the conductor 80 joining the 'I'he electrodes 13 and 14 are connected tothe other terminals of the lamps II and I2 by conductors 8l vand 82, respectively.

The plunger 18 is constructed so that when it is in its lower position (Fig. 1), the electrode main circuit, .the latter circuit may be traced from the secondary coil 69, thru the conductor 18, electrode 15, mercury 18, electrode 13, conductor 8|, lamp II, conductor 80, conductor 43,

track relay 20, conductor 44, and back to the A ,are electrically connected by the mercury. The

circuit may then be traced from the secondary coil 89 through conductor 19, electrode 15, mercury 15, electrode 14, conductor 82, lamp I2, conductor 80, conductor 43, track relay 20, conductor 44, back to the secondary coil. Therefore as the plunger 18 is reciprocated within the envelope, the lights I I and I2 are alternately flashed.

The switch I3 may be of the type shown in my copending application, Ser.- No. 636,288, led October 5, 1932, the speciilc form being shown in Figs. 7 to 12 'of that application. It will be understood that the switch is so formed that whenever the plunger changes its position, there will always be an intermediate position, such as shown in Fig. 5, at which time, the electrodes 13 and 14 are both out of contact with the mercury. f Y

The solenoids 48 and 49 may have the same characteristics as previously given for the solenoids and 41.

In place of the three-electrode switch shown in Figs. l, 5 and 6, it is possible to substitute front and back contact mercury switches, such 'as shown in Figs. '7v and 8. In this arrangement,

the front contact switch indicated at 83 is provided with electrodes 84 and 85 which are disconnected from each othervwhenever the solenoids 48 and 49 are deenergized (Fig. '7.) Under such circumstances, the plunger 86 iloats high upon the mercury 81. Y

When the solenoids 48 andv49 are energized, the plunger 88 is drawn downinto the mercury and the electrode 84 is then .covered with mercury, as seen' in Fig. 8; The pole sleeves 66 and 89, which) are made of magnetic material,

serve to fix the air gap at the desired place with 5 reference to the electrode 84.

The back contact switch 90 has electrodes 9| and 92 which are adapted to be bridged by the mercury 93 within the Venvelope whenever the solenoids-48 and 49 arede-energized. When the plunger is, drawn up 'by the energization of the solenoids (Fig. 8) the mercury recedes from the electrode 9| and the connection between the 'electrodes 9| and 92 is broken. The

pole sleeve 94 serves to ilx the position of the air gap.

The pole pieces 95 and 96 used with separate front and backcontact switches differ from the pole pieces 91 and 99, shown in-Fig. 1 and Fig. 9, only by being provided with suitable apertures for the extra switch.

As shown in'Fig. 7, the electrode .84 of the switch 83 and the electrode 92 of the switch 90 are connected by a conductor 99 which in turn is connected to one side of the secondary coil 69 of the transformer 10. The lamps II and I2 have one terminal each connected to the electrodes 85 and 9|, respectively, while the other terminal of each lamp'v is connected by a `conductor 80. The conductor 43 leading to the track relay 20, which in turn is connected by 'conductor 44 to the other side ofthe secondary coilm69, completesthe circuit.

. Structure The cores |03 of the respective solenoids have K both ends threaded, the inner ends passing through the insulating plate IOI and screwing into fthe pole pieces 5I, 52, 91 @and f,98; and the other ends passing through the bars 53 and |02 and fitted with nuts. A bar V|04 of nonmagnetic material (Fig. 9) is placed between the pole `pieces 5I,' 91 and 52, 98, respectively, in order td prevent the pole vpieces from being rotated and possibly breaking the switch tubes.

The circuit breaker I0 and switch I3 l:are mounted in their respective pole pieces and held in place by the bakelite sleeves 61. The electrode 56 of the circuit breaker i0 is connected 60 to a binding post |05 and the other electrode 55 is connected to a binding post |06 which connects the twogroups of solenoids. The electrode 15 of the switch I3 is connected to a'pindving post |01, the electrode 14 to a binding post l 65 |08, and the electrode 13 to a binding post |09.

75 As seen in Fig. 10, binding posts |06 and II5 arel connected .to the battery 45; the binding posts |01 and ||0 are connected to the secondary coil 69, and the track relay, respectively;

the'. binding posts |08 and II2 are connected-i to the lamp I2 and the binding posts II3 and I 09 are connected to the other lamp II.

'I'he ashing light signal which has just been described has fewer parts than the mechanical iiashers heretofore employed, and in addition has far greater reliability in operation. It is, of course, understood that the device is not limited to use at railroad crossings, but may be used wherever a ilashing signal is desired. I1'

the device is used fto protect dangerous points 1. A mercury switch comprising a glass envelope, a quantity of mercury'therein, a displacer floating on the mercury, electrodes pro-- jecting into the envelope adapted to be bridged by the mercury when the displacer is in its depressed position, said displacer comprising a part of this' sleeve adapted to telescopeover one of the electrodes and being relatively thick above the mercury level and relatively thin below said level.

2. A plunger for use in a mercury switch, said plunger comprising a sleeve having its upper portion of substantially greater thickness than its lower portion, said plunger being closed at its upper end except fora restricted passage.

3. In an electromagnetic switch, a coil, a switch envelope, a quantity of mercury therein, electrocles projecting into the envelope and normally bridged by the mercury, a ldisplacer oating on the mercury adapted to be raised to cause the mercury to recede 'in the envelope and break the connection between the electrodes, a time delay element associated with the displacer, said displacer comprising a sleeve having substantially greater mass at 'the top than at /the bottom so that when the displacer is released from its raised position, 4it will fall at once to the 'floor of the, envelope without coming to a position of floating equilibrium during its downward travel, and means for cushioning the fall of the displacer.

4. In an electromagnetic switch, a coil, a`

switch envelope, a 4quantity of mercury therein, electrodes projecting into the envelope and nor;

mally bridged by the mercury, a displacer floating on themercury adapted to be raised to cause the mercury to recede in the envelope and break the connection between the electrodes, a time delay elementassociated with the displacer, said displacer comprising a sleevehaving-substantially greater mass at the top than at the botistvv tom so that when the displacer is released from its raised position, it will fall at onceto the floor of the envelope without coming to a position of floating equilibrium during its downward travel,

and means for cushioning the iallbf the displacer, said means includinga spring interposed between the displacer and the oor 'of the envelope.

5. In an electromagnetic switch, a coil, a. switch envelope, a quantity of mercury therein, electrodes projecting into the envelope and normally bridged by the mercury, a displacer iioating on the mercury adapted to be raised to cause the mercury to recede in the envelope and break the connection between the electrodes, a time delay element associated with the displacer, said displacer comprising a sleeve adapted to tele# scope over one of the electrodes and having substantially greater mass at the top than at the bottom so that when the displacer is released from its raised position, it will fall at once to the iioor of the envelope without coming to a position of iloating equilibrium.

6. In an electromagnetic switch, a coil, a switch envelope, a quantity of mercury therein, a displacer for shifting the mercury level, a time delay element associated with the displacer, electrodes projecting into the mercury adapted to be bridged by the mercury when the coil is de-energized, said displacer having its upper portion of substantially` greater dimensions than its lower portion so that when the coil is energized, the displacer will move promptly to its raised position after which the time delay ele-l ment functions to provide a time interval before the circuit is opened, and when -the coil is thereafter, de-energized the displacer will fall promptly to the floor of the envelope after which the time delay element functions to delay the closing of the circuit.

7. In an electromagnetic switch, a. coil, a switch envelope, a quantity of mercury therein, electrodes projecting into the envelope adapted to make or break an electrical circuit accordingto the mercury level, a displacer telescoped over one of the electrodes and responsive` to the coll for shifting the mercurylevel, a time delay element associated with the displacer, said clisplacer having its mass so distributed with reference to the mercury level and the electrodes that movement of the displacer in both directions in response to the coil is characterized by relatively quick positive action to the full extent of the displacer travel after which the time delay element effects the delay in changing the condition of the circuit. i

, so distributed with reference to the mercury level and the electrodes that movement of the displacer in both directions in response to the coil is characterized by relatively quick positive action to the full extent of the displacer travel, after which the time delay element effects the delay in changing the condition of the circuit.

9. In a mercury switch, a switch envelope, a mercury iill, two or more electrodes adapted to be bridged under certain conditions by the mercury to close an electrical circuit through the switch, a displacer adapted to be raised by magnetic `force and lowered by gravity to change the level of the mercury and hence the condi.

tion of the circuit through the electrodes, said displacer having substantially more mass above the high, mercury level than below said level, so that when the displacer is released from its raised position it will immediately fall to its lower position with a sharp quick movement.

10. In a mercury switch, a switch envelope, a mercury fill, two or more electrodes adapted to be bridged under certain conditions by the mercury to close an electrical circuit through the switch, a displacer adapted to be raised by magnetic force and lowered by gravity to change the level of the mercury and hence the condition of the circuit through the electrodes, said displacer having substantially more mass above the high mercury level than below said level so that when the displacer is released from its raised position, it will immediately fall to its lower position with a sharp quick movement, and a time delay element associated with one of the electrodes. l

CARL H. LARSON. 

